


Whistle Baby

by In_the_aroace_brigade



Category: Undertale (Video Game)
Genre: Accidental Voyeurism, Dom/sub Undertones, Ecto-Penis (Undertale), Ecto-Tongue (Undertale), Fontcest, Gags, Hickeys, Kind of a songfic?, Light Bondage, M/M, No Tentacle Sex, Oral Sex, Orgasm Delay, Sadbros/Stonerbros, Size Difference, Smut, Soul Sex, Tentacles, almost getting caught, slight edging
Language: English
Status: In-Progress
Published: 2016-06-27
Updated: 2016-06-28
Packaged: 2018-07-18 13:37:29
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 4,322
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7317394
Author URL: https://archiveofourown.org/users/In_the_aroace_brigade/pseuds/In_the_aroace_brigade
Summary: <blockquote class="userstuff">
              <p>Sans reached up to grab onto Papy’s hoodie, meaning to push him away and take back control, but Papy let go of his skull and grabbed both his wrists in his hand, pulling them up above his head. Sans whimpered and Papy nuzzled his neck. “Shhhh, none of that now. Don’t worry, I’m going to take good care of you.”</p>
            </blockquote>





	1. I'll blow your whistle...

**Author's Note:**

> This happened on accident I swear. I sat down to write another chapter of Getting Lost; Being Found and instead I wrote my first fontcest *facepalms* So you guys get to have this while I try that again.
> 
> Many thanks to UndertailSoulSex, SansyFansySkele, PurrfecktlySinful, and Spiderdickens for helping me make this actually happen, along with my friend that described his opinion of a perfect blow job and another friend that literally sat down with me and showed me youtube videos of people describing how to give a perfect blowjob. I have seen things I cannot unsee. #Isufferedformyart

_Can you blow my whistle baby, whistle baby  
Let me know_

Sans breathed in deeply as the other version of his brother gently pushed him back onto his unkempt bed, easing him so that he was lying flat on his back. Papyrus, or Papy as he was often called, bumped his teeth to Sans’ in a skeletal kiss and worked his way down his neck, tugging the sweatshirt to the side so he could reach Sans’ collarbones. “Ahhh” Sans gasped as Papy released his mouth from around his clavicle, a small kiss easing the bite mark he left. Papy continued down Sans’ body, licking and biting at his sternum and ribs as Sans’ squirmed beneath him, large hands pinning down the small body. Papy made sure to take his time on each individual bone, never continuing to the next until he was sure that he had discovered every last spot on Sans’ chest that made him move so beautifully underneath him.  A gentle glow was starting to shine from Sans’ chest with another beginning to brighten in a place a little lower.  
  
_Girl I'm gonna show you how to do it  
And we start real slow_

Papy grinned and reached a hand down to Sans’ pelvis, skirting around the top of his waistband. Sans opened his mouth to complain but Papy took the opportunity to slip his own translucent orange tongue besides Sans’ blue appendage, dominating his mouth and silencing any protests. Papy traced circles on Sans’ ASIS with his right hand, his left being used to cradle the smaller skeleton’s skull and pull him further into the kiss. Sans reached up to grab onto Papy’s hoodie, meaning to push him away and take back control, but Papy let go of his skull and grabbed both his wrists in his hand, pulling them up above his head. Sans whimpered and Papy nuzzled his neck. “Shhhh, none of that now. Don’t worry, I’m going to take good care of you.”

Sans groaned as Papy finally brushed against his newly formed member, the friction from his gym shorts almost harsh against his sensitive head. Papy covered Sans’ mouth with his own again, drinking in the sounds from the shaking figure beneath him. He cupped his fingers around Sans’ cock and stroked upwards. “paaAAAPP” Sans moaned, attempting to buck his hips up into the other’s perfectly positioned phalanges.

Papy tutted and moved his hand away from Sans’ penis and grabbed his femur harshly, pushing it into the soft mattress below them. “Now, did I say to do that? I don’t know that you deserve that just yet, you keep misbehaving. Now you are going to sit back and let me take my time enjoying you, or I might just decide that I’m needed somewhere else for a little while and leave you here with no relief.” Papy leaned his face in towards Sans’, eye sockets locking on the blue blushed face before him. “Understand?”

Sans whimpered and nodded, tears beginning to run down his cheeks from the lack of stimulation. Papy licked up his tears and kissed Sans’ forehead, his right eye lighting up with his orange magic. Sans shivered as he felt something creep along his side, slithering up to where his wrists were held captive in Papy’s hand. Glancing sideways he sees an orange tentacle that has seemingly sprung up from the bed itself. Before he can shout his surprise, there is another at his mouth, covering it in its entirety so he can only breathe from his nose. Sans tries to glare at Papy, who looks back with a lazy smile on his face as another gleam in his eye has two more tentacles sprouting from near Sans’ hips. “Comfortable so far?” Papy asked, caressing Sans’ pelvis which was still covered by his shorts. Sans moaned and bucked his hips, attempting to get the friction he so desperately needed.

Suddenly his head was pulled more forward by the tentacle surrounding his face and brought him face to face with the one who had brought him to this point. “Sans, I need to know if you are comfortable with what I am doing. Shake your head yes or no.” Papy’s voice was stern but caring, and Sans blushed before nodding yes, he was doing fine. “Good!” Papy smirked, allowing Sans’ head to rest back on the bed. The tentacle that had been creeping towards Sans’ hands began to weave in and out of his radius and ulna on both arms, effectively binding them to each other and the bed. Papyrus relaxed his grip and leaned back, taking in the view before him. Sans lay flat on his back, blushing and squirming away from the two magic tentacles near his hips that had begun to tease his pelvis and lower spine, gently brushing up and down the vertebrae. Papy caressed Sans’ member outside his shorts once more and noted the growing wet patch and licked his teeth. Sans was ready.

  
_You just put your lips together  
And you come real close_

Papy stopped his magic from stroking Sans’ pelvis again and instead placed his own hands on the waistband of Sans’ shorts again. This time, however, he gripped the fabric and pulled downwards, watching with satisfaction as the blue member sprung free from its prison, gently bobbing before coming to a rest, magic dripping out of the tip. Sans’ moaned around his gag and kicked out with his feet, relieved that the taller skeleton was finally in the area that he needed him the most. Papy caught his heels and held them still while easing the shorts the rest of the way off his body, going slow to frustrate Sans further. Once the shorts were all the way off he pulled Sans’ legs apart to get a clear view of the glowing pelvis, then leaned in and nibbled Sans’ sacrum. Sans twisted and kicked his legs again, unable to hold himself still while trapped in this pleasure. Papy simply smiled and pulled Sans’ femurs apart even further before having his magic wrap around them, keeping the blue-blushed skeleton spread nice and wide for him.

Papy shed his jacket, the room feeling strangely warm by that point. Sans groaned at the site of the tall skeleton in just a black tank top, able to see all of the gorgeous bones but unable to touch them. He tried pulling against the tentacle restraining his arms in hopes that Papy had lost his concentration, but that just made them hold on all the tighter then begin a pulsing rhythm on his bones. The tentacles around his legs began pulsing as well, relaxing the pent-up skeleton and leaving him incapable of conscious movement.  

Papy turned back to the petite body and let his fingers slide against Sans’ ribs, slipping down his spine until they reached the lumbar vertebrae and sacrum. Papy decided that he wanted to take his time, having finally convinced the individual before him that he was serious about wanting something more in their relationship and would be able to care for Sans like he deserved. This wasn’t the first time that they had engaged in such activities, but Sans had never given over so much control as he had now. Papy was determined to make sure that this would be the best orgasm Sans had ever achieved. He began by softly grazing the edge of the pelvis, keeping his touches light on the small one’s body. He took his time, using just a single finger on his right hand to trace over every part of the bone while ensuring to avoid even brushing against Sans’ magic, wanting to edge the skeleton ever further.

Sans’ cock was weeping by this point and even his soul was beginning to drip magic onto the sheets below them. Sans himself was unable to even keep up a regular breathing pattern; when Papy noticed this, he released the tentacle around Sans head and tenderly rubbed his skull, placing his mouth near Sans’ head and reminding him quietly “You need to breathe, babe. Just in and out.” He placed his other hand on Sans’ sternum, Sans’ whining from the contact. “Come on, you can do this.” Finally Sans was able to control his breathing on his own and Papy moved back down to his pelvis, this time able to enjoy every sound that resulted from his touch. Realizing he wanted Sans to see himself come apart, he pulled the little skeleton upright against his chest, Sans unable to resist any movement. Papy carefully rearranged the pillows to support Sans’ body then laid him back against them, allowing his magic to readjust itself so that the tentacles could still hold Sans in place. Sans pushed his head forward for a kiss and Papy indulged him before licking a stripe down Sans’ neck and chest, stopping at the bottom ribs. “Keep your eyes on me” was all Papy said before leaning over Sans’ pelvis to begin nibbling along the top.

“aahHHHHH, PAAAPPYYY” Sans cried out, almost coming right then. Papy looked smug as he used his tongue to flick in and out of the holes on Sans’ sacrum, nipping at his coccyx as he did. He made sure to look up at Sans’ face every once in a while, wanting Sans to have to make eye contact with the one who was making him sob and writhe against the wall. Papy began to bathe his pelvis, latching onto the bone and sucking hard. Some of Sans’ pre-come dripped onto the pelvis and Papy licked it up, letting orange mix with blue on his tongue. He lapped up what he could and tilted his head up towards Sans, demanding entrance to Sans’ mouth. Sans let his jaw drop open and Papy stuck his tongue in, allowing Sans to taste the mixture of their magics. Sans shuddered as the hem of Papy’s top brushed against the head of his cock, creating an unseen stain on the fabric.

Papy passed the last of the magic into Sans and went back to working on the pelvis, working closer and closer to the proud member dribbling out a constant stream of magic. He was starting to leave light bruises on the bone from the force of his sucking, all in an attempt to draw out the loudest sounds possible from his partner. He finally kissed Sans’ pubis just below the base of his member, then latched onto the bone and sucked as hard as he could. San’s eyes rolled into the back of his head as he came, screaming out Papy’s name. San’s soul came apart as well, magic exploding from the center of his chest and landing all around them. Papy reached up and touched the top of his own skull and wiped some of the magic off, then tasted it. He turned to Sans and stuck his fingers in his mouth, a silent order for Sans to clean them off. Sans did the best he could, barely present in the moment.

“I don’t remember saying you could come, but I’ll forgive you this time. However, I still haven’t gotten what I wanted yet so you are going to have to put up with another orgasm.” Papy trilled, watching as Sans’ eyes widened from their half slitted gaze, protests muffled by Papy’s fingers in his mouth. Papy slyly grinned as he brought Sans’ soul out from his chest, blue magic a stark contrast on his white phalanges. He began to suckle on the soul, licking off the excess magic leftover from Sans’ orgasm. Sans’ began to struggle against the tentacles, unable to escape the unrelenting feeling washing through him from Papy’s tongue. Quickly Papy’s goal was achieved and Sans’ member was standing proudly once more while the soul nestled in his hand continued to weep magic, staining the white bone.

  
_Can you blow my whistle baby, whistle baby  
Here we go_

Papy pulled his fingers from Sans’ mouth and wiped his other hand on his own shirt before pulling Sans’ knees up so they would be pressed near the sides of his ribs. He then reached his hands around Sans’ pelvis to cradle it and hold it perfectly still before swirling his tongue around the head of Sans’ penis. He had to tighten his grip on the bone when Sans’ contorted himself upwards in an attempt to shove the rest of his cock down Papy’s throat. Papy allowed another tentacle to come and slither up Sans’ spine, twisting between the ribs along his back. He shifted his grip to the base of Sans pelvis while gently licking up and down Sans’ member, kissing the tip each time he reached the top. He opened his mouth while over the top of Sans’ penis and allowed his saliva to drip down in preparation for later. He was trying to cover the surface but soon realized that it wouldn’t be quite enough. While continuing to wrap his tongue around Sans, he reached up with one hand and cupped Sans’ soul, using his thumb to rub against it. Sans gasped and groaned, his soul quickly responding by soaking Papy’s hand. He swiftly brought his hand back and began to work it up and down Sans’ dick, rubbing his own soul magic onto it to lube it up.

Once he deemed it to be sufficient he circled the base of Sans’ member with his index finger and thumb of his right hand, holding it firmly enough to prevent Sans’ from coming early again. He flicked his eyes up to Sans and stared at him while opening his mouth and sinking down onto Sans, managing to relax his throat enough to kiss his own hand before easing up and down along his shaft. He whirled his tongue around, sometimes pulling up enough that he could tease Sans’ slit with the tip before bobbing back down to where his usually invisible throat would press against the head. Sans was sobbing and screaming now, voice growing hoarse from the shear amount of noise he was making. Papy brought his other hand up to move in tandem with his mouth, ensuring that a constant pressure would be maintained. His other hand continued to grip the base, not quite ready yet for Sans to release.

Papy managed to maintain Sans’ state for several minutes, keeping a steady eye on his soul to determine when it was becoming too much. Finally it got to the point where Sans’ soul was almost blinding in its glow and the skeleton himself was trembling and unable to form words. Papy took his mouth off of the head of Sans’ cock, saying “You may come now, Sans.” With that, he took both his hands off of Sans’ member and instead enveloped it with his mouth, sucking hard once he had reached the base. Sans howled and came apart underneath him, come shooting down Papy’s throat while the top of his skull was splattered with the magic from Sans’ soul.

Papy dispersed his magic and gathered up the small panting skeleton into his arms, twisting so that it was his own back against the pillows and Sans was huddled on his lap. Papy rubbed Sans’ scapulae with one hand while reaching over and searching for a blanket to wrap around his partner. He came across something soft and pulled it up, discovering it was his own sweatshirt. Papy shrugged and wrapped it around Sans’ heaving body, rubbing Sans’ shoulders and pulling his head down to rest against Papy’s collarbone. Slowly the small body’s breathing slowed and Sans began nodding off in Papy’s lap while the tall skeleton pressed kisses against his head. Papy attempted to shift Sans off of him so that he could get up to grab a washcloth to clean Sans and himself up but two small hands reached out and grabbed his shirt. “no. stay.” a sleepy voice demanded. Papy smiled and resettled back in, cradling Sans in his arms. Clean up could wait; right now, Sans needed him.

 

BONUS CONTENT:

Papyrus strode up the stairs, a worried look on his face. Someone had mentioned in passing that they had heard screams coming from his house. He knew that Sans was perfectly able to take care of himself and that the other version of himself was there as well, but still, it couldn’t hurt for the Great Papyrus to check, right?  
He tried the knob of his brother’s door and found it locked as always. Knocking, he called out “SANS? PAPY? IS EVERYTHING ALRIGHT IN THERE?” After a couple seconds of receive no answer Papyrus grew even more worried and summoned a bone construct, bringing it down against the lock. The lock fell apart and Papyrus barged in to find two startled skeletons lying on the bed. “SANS? PAPY? ARE YOU OKAY? SOMEONE HEARD NOISES FROM OUR HOUSE EARLIER AND I WANTED TO MAKE SURE THAT YOU TWO WERE OKAY.”

Sans’ face flushed blue and Papy’s cheeks tinted orange. “yeah Pap, everything is okay. we were…just watching a movie, guess it was too loud. sorry that we pulled you away from your patrol.”

Papyrus grinned. “IT IS QUITE ALRIGHT, I HAD FINISHED FOR THE DAY ANYWAYS. BUT SANS, YOU ARE ALL BLUE, ARE YOU SURE YOU ARE OKAY? PAPY, YOU ARE BLUE TOO, BUT ONLY ON THE TOP OF YOUR HEAD. ARE YOU BOTH TOO COLD? NEVER FEAR, THE GREAT PAPYRUS IS HERE TO HELP. LET ME JUST GO GET SOME MORE BLANKETS AND TEA, AND A HAT FOR PAPY.” Papyrus ignored their sudden exclamations and protests, practically running out of the room. It was clear that Papy couldn’t properly take care of Sans (even if he had given him his sweatshirt) or himself. Luckily they had such a cool guy there to help them.


	2. Chapter 1.5: A "Rocky" Time

**Notes for the Chapter:**

> THIS IS ALL YAOIADDICTION'S FAULT. They wanted a fic that included the pet rock into the smut. So have this terrible sin (but don't read it if you want to keep your sanity).

Rocky's POV

He had been moved up to Sans' room when the other skeletons began to visit more so that there would be more room downstairs for company. He hadn't minded at first, Sans would give him a bit more attention up here, remembering to pet him occasionally and throwing some leftovers his way (not that he could eat them, but it was the thought that counts). He knew that Sans had started seeing the laid back version of his brother but the most he had seen so far was just them kissing and cuddling on the bed. Sometime last week Sans had turned him around for a few hours so all he was facing was the wall. He wasn't sure what all happened then but the bedroom glowed a lot and he felt something wet along his back. They also made a lot of strange noises and moved a bunch. _Maybe they were just playing with water guns and flashlights, it seems like something they would do._

It was another boring afternoon when the two skeletons entered the room, teeth pressed against each other, the taller orange clad skeleton leading his owner to the bed. Rocky watched with interest at this new behavior from the two. His owner was already moaning and gasping, crying out the tall skeleton's name as he squirmed against the sheets. Papy consoled him and used his magic to make tentacles appear, holding down his owner. Rocky was concerned but Sans seemed to like it so he decided to simply sit back and watch. He knew that the tall skeleton was very fond of Sans but he wanted to be sure that he was treating his owner with the respect he deserved.

Rocky watched as his owner slowly but surely began to fall apart under the other’s expert touch. The gag around Sans’ mouth kept him from voicing his pleasure but both his chest and pelvis were glowing brightly. _I know his soul is in his chest but what else is his magic doing?_ Rocky wished that he could lean closer into the scene happening before him. Currently Sans’ legs were in the way, but it looked like Papy was repositioning them? Oh! He was taking off Sans’ shorts. Rocky would finally be able to see what was glowing on Sans’ pelvis. Soon his owner’s shorts were tossed off to the side and Papy was using his magic to hold Sans’ legs open. Rocky had a small window left under Sans’ leg that he could watch everything that Papy was doing to his owner. It turned out that the light was coming from a thick oddly shaped blue glowstick that was leaking its contents. It was the same color as Sans’ magic so he supposed that his owner had made it for some purpose.

Papy took a moment to take off his sweatshirt before starting to use his mouth on Sans’ pelvis. Rocky was shocked, this was very different than anything they had done before. His owner was writhing against his partner’s magic while Papy used his tongue to lathe affection onto Sans. The display was causing Rocky to feel something that he had never experienced before. He almost felt like the air pressure had increased around him. Unable to voice his concerns, he simply stared googly-eyed as Papy released the tentacle gagging Sans and murmured softly to him. Rocky couldn’t hear what was said but soon Sans’ breathing had calmed down and Papy had settled back into his pelvis. This time when Papy lavished Sans the small skeleton screamed out until Papy kissed him again, pushing his tongue into his owner’s mouth.

Sans’ wails were all the louder once Papy finished up top, however, and when the tall skeleton latched onto the bone beneath the blue glowstick his owner’s soul drenched the area in blue and the glowstick shot magic out of its top, the force sending it arching a couple feet into the air. Papy’s skull was covered in magic from Sans’ soul and the tall skeleton reached up and wiped some of it off. He put some of it in his own mouth then stuck his fingers in Sans’ mouth. Even Rocky hadn’t been spared and the sudden wave of magic had landed on him as well, staining part of his surface blue. The sudden drenching had just increased the feeling of pressure and left him wanting something more. Luckily it appeared that Papy felt the same as the other version of his owner’s brother reached into Sans’ chest and pulled out his soul, licking it like an ice cream cone until the blue glowstick was back and bigger than ever.

Papy pushed Sans’ knees even further into his chest, allowing Rocky a beautifully unobstructed view. Rocky didn’t realize that he had harbored this kind of wanting from his owner, but now that it had been offered Rocky planned to take full advantage of the opportunity. Papy was gripping Sans’ pelvis while he lowered his head to take the glowstick into his mouth. Rocky was pretty sure that glowsticks were poisonous but perhaps since it was made from his owner’s magic it wouldn’t have the same problems. The tall skeleton really seemed to like it but looked pensive until his face settled and he reached a hand up into Sans’ chest once more to collect some of Sans’ magic straight from his soul. Once he had filled his hand he brought it back down and rubbed it onto the glowstick. All of this was making his owner hoarse with the plethora of noises coming from him.

Eventually Papy paused his movements with his hand and mouth and whispered something to Sans. Once more the room was awash with a blue glow and this time the magical explosion reached even further. Fortunately Papy made clean up easier by eating whatever had come out of the glowstick. Meanwhile Rocky himself had undergone something strange as soon as some of Sans’ magic hit him again. All of the pressure he had been feeling had continued to increase until euphoria washed through him and all the pressure left all at once. If Rocky had had lungs he was sure he would be gasping for air just as his owner was doing now. Papy had wrapped Sans’ up in his sweatshirt and was hugging his owner. They settled in for a nap and Rocky was rather jealous that he didn’t have anyone holding him. Instead he settled for trying to recreate the feelings he had experienced. _I hope they forget about me being here more often._

 

 

BONUS  CONTENT: 

Rocky had woken up when his master’s boisterous brother burst into the room, yelling something about the cold then ran back out again. He had planned to settle back into a nap when Papyrus was back, bundling both of the skeletons in blankets and shoving a hat on Papy’s head. Both of the skeletons were blushing but the hyper skeleton just took this as a sign that something was wrong, picking them off the bed and shuffling them out the door to go sit on the couch while Papyrus made tea. Before they could leave the room, Papyrus noticed Rocky where he was trying to sleep. “SANS? WHY IS ROCKY ALL BLUE AS WELL? I THOUGHT ROCKS COULDN’T GET BLUE WITH COLD! SHOULD I WRAP HIM IN A BLANKET AS WELL?”

His owner looked startled for a second and locked eyes with Rocky from his spot near the doorway. “nah bro, i think he just needs a bath. i was…messing around…with my magic near him earlier and must have not had good enough control.”

Papyrus tutted and exclaimed “BROTHER THIS IS WHY I KEEP TELLING YOU TO WORK ON YOUR MAGIC CONTROL! I’LL TAKE CARE OF ROCKY FOR NOW BUT TOMORROW WE ARE PRACTICING AND YOU ARE NOT GETTING OUT OF IT THIS TIME.” Neither of the flustered skeletons had time to respond before Papyrus scooped him up and returned to them, practically carrying them out the door and down to the couch. _I guess my nap will have to wait._

**Notes for the Chapter:**

> I TOLD YOU NOT TO READ IT BUT NOOOOOOOOOOO YOU HAD TO DO IT ANYWAYS. NOW YOU HAVE TO REMEMBER THIS AS SOMETHING YOU READ.
> 
> Also magic blue glowstick pffft.

**Author's Note:**

> So I realize that the fic doesn't quite fit the song perfectly so hopefully I will be able to produce a Chapter 2 that will fit it a little better, but I make no promises currently.
> 
> My tumblr is [accidentalfeelfest](http://accidentalfeelfest.tumblr.com/)
> 
> Song chorus from "Whistle" by Flo Rida


End file.
